* cppexp.c (lex): Move some code to _cpp_parse_expr, but
	keep most cases as function eval_token.
	(eval_token): New function.
	(_cpp_parse_expr): Read token here for improved diagnostics.
	Don't use op_as_text.  Detect bad ':' here.
	(reduce): Don't detect bad ':' here.
	(op_as_text): Remove.
	* cpphash.h (_cpp_test_assertion): Change prototype.
	* cpplib.c (_cpp_test_assertion): Change prototype.
testsuite:
	* gcc.dg/cpp/if-cexp.c: Add a test.

From-SVN: r52866